Tape cartridges in use today incorporate a magnetic tape having data tracks for recording a succession of units of information known as data sets. Each data set consists of a data region within which data is recorded and a data set information table that describes the content of the data region. Data to be recorded is sent to the cartridge by a tape drive and is recorded within the data regions. The data set information table for each data set has a multiplicity of fields each of which has a pre-allocated number of bytes of storage. The fields store records of information such as the data set number, the valid data length, the data set type, and the drive manufacturer identity.
Data written to the tape may be protected from being overwritten. Such data is protected by drive level processing that renders the tape as write-once-read many (WORM) protected. When trying to protect data written to tape in a WORM environment, safeguards are implemented to prevent the data from being overwritten, accidentally or intentionally.
Tape cartridges typically comprise a memory device such as a memory circuit which is mounted in the casing of the tape cartridge. Such a device is usually referred to as a “cartridge memory”. The cartridge memory typically comprises a memory circuit module such as an EEPROM semiconductor memory chip and a transponder. The transponder is powered by and exchanges information with a reader/writer device via an inductively coupled interface. The cartridge memory can be used to store many types of information including usage information, cartridge manufacturer information and cartridge memory manufacturer information. The cartridge manufacturer information includes the cartridge type, a serial number of the cartridge and an identification of the manufacturer. The cartridge memory manufacturer information includes the serial number of the transponder, the type of transponder and the serial number of the cartridge memory.
The safeguards to prevent overwriting of WORM protected data include providing information in the cartridge memory to inform the drive that the cartridge is WORM protected. It may however be possible to tamper with the cartridge so that either information in the cartridge memory is altered or the cartridge memory is swapped for another such memory, thereby allowing the unauthorised overwriting of data that should be WORM protected.
U.S. Pat. No. 6,674,596 describes a tape drive unit that stores data in a magnetic tape cartridge incorporating a cartridge memory built into the cartridge. A cartridge serial number is stored in the cartridge memory and is written on the magnetic tape. When the cartridge is loaded into a tape drive, the serial numbers are compared and reading data from or writing data to the tape is inhibited if the cartridge serial number in the memory does not coincide with the cartridge serial number on the tape.